Tinea corporis, tinea cruris, and tinea pedis are of the most prevalent dermatophytoses. Several conditions that mimic dermatophytoses and atypical and steroid modified forms of the disease usually present difficulties in diagnosis. Hence, the present investigation aimed at studying these conditions on mycological basis. The study included 163 cases clinically diagnosed as having tinea corporis, tinea pedis or tinea cruris. Specimens were taken by skin scraping. Samples were cultured on Sabouraud's dextrose agar and examined microscopically. The results revealed that, only 90.8% of cases were mycologically proven (positive by one or both methods). Most of tinea corporis, tinea pedis and tinea cruris cases (68.9%, 79.1%& 83.9% respectively) were diagnosed by both methods (P>0.05). For cases of tinea corporis and tinea cruris, males were more than females (51.4%, 48.6% and 58.1%, 41.9% respectively) while females exceeded males (72.1%, 27.9% respectively) in cases with tinea pedis (P<0.05). Trichophyton rubrum (T. rubrum) was the most common isolate in all the studied conditions, represented 64.9% in tinea corporis, 53.4 %, for tinea pedis and 64.6% for tinea cruris. T. mentagrophytes var. interdigitale was mostly isolated from cases of tinea pedis (23.3%). The majority of T. violaceum was isolated from cases of tinea corporis (12.2%). The main isolation of E. floccosum was from cases of tinea cruris (16.1%) Microsporum canis (M. canis) was only isolated from one case (1.4%) of tinea corporis while Candida albicans (C. albicans) alone (9.3%) or with T. rubrum (7.0%) was isolated only from cases of interdigital tinea pedis. (P<0.05). The majority of cases of tinea corporis, tinea pedis and tinea cruris had chronic lesions (78.4%, 76.7% and 54.8% respectively) (P<0.05) and received prior therapy for the condition (79.7%, 76.7% and 58.1% respectively, (P>0.05). In conclusion, early accurate diagnosis (on mycological basis) is an important tool to control and reduce the incidence of dermatophytosis. Periodic epidemiological analysis of these conditions is required to ensure their efficacious control.