A review of mycobacteria isolated from clinical samples from the Western Health Board Area (WHBA) for the years 1986 to 1990 was performed to establish the pattern of mycobacterial infection. The incidence of microbiologically proven cases of tuberculosis (13.3/100,000) and of sputum smear positive cases (6.2/100,000) was determined and correlated with notification data. M. bovis accounts for 6.3% of cases of microbiologically confirmed tuberculosis in this area. Resistance to one or more of the first line anti-tuberculous drugs was noted in 5.3% of isolates (excluding pyrazinamide resistance in M. bovis). Clinically significant isolates of mycobacteria other than tuberculosis (MOTT) were rare throughout the five year period. The overall incidence of microbiologically proven cases of tuberculosis is relatively high and M. bovis and drug resistant isolates of M. tuberculosis are relatively common.