Abstract African walnut (Tetracarpidium conophorum Mull. Arg) is commonly processed by boiling or toasting and consumed as a snack or used as a thickener in many West African soup preparations. The nuts are usually exposed to both high temperatures and high relative humidity in open markets which predisposes them to fungal growth. Hence, the dangers of spore inhalation and resultant mycosis cannot be over-emphasized as retailers and consumers are always in direct contact with these nuts during harvest, processing and consumption. So far, there is no reported research on potential mycotoxin contamination of African walnut and whether this risk might be accentuated by processing. African walnut, at early and late maturity stages, were processed by toasting, boiling or left unprocessed before being stored at 25 °C and 37 °C, respectively under controlled relative humidity for 7 days. Nuts were cracked and shell pieces cultured in Malt Extract Agar (MEA) and Dichloran Glycerol 18 (DG18) media and incubated at 25 °C for 7 days. Results revealed that potential mycotoxigenic species - Aspergillus section Nigri, Aspergillus flavus/parasiticus, Fusarium spp. and Penicillium spp. - were frequently isolated. When compared with unprocessed nuts, toasting completely prevented fungal contamination in shell pieces from nuts in the non-stored (NSN) group at early maturity stage, while boiling significantly reduced the level of contamination to about 58 % (P < 0.05). In general, simulating open market conditions caused 100 % fungal contamination in all boiled samples and toasted samples at early maturity. However, contamination in toasted samples at late maturity was increased to 90 and 70 % at 25 °C in DG18 and MEA, respectively, while at 37 °C contamination was 40 and 60 % in DG 18 and MEA, respectively. Mycotoxin analysis using Yeast Extract Sucrose agar (YES) and High Performance Liquid Chromatography (HPLC) - Fluorescence detector (FLD) showed that Aflatoxins - G1 (AFG1), B1 (AFB1), G2 (AFG2), and B2 (AFB2) were produced by 20 isolates with both AFG1 and AFB1 being predominant at concentration ranges 4.33 – 32,200 and 4.20 – 22,700 ng/g plug weight, respectively. No Ochratoxin A (OTA) was detected out of 23 isolates analyzed. From these findings, it is suggested that toasting of nuts, preferably at early maturity is a safer processing option than boiling in terms of prevention of possible fungal growth on nut shells and risk of mycotoxin contamination.