Nocardiosis is an increasingly recognised opportunistic infection in immunologically incompetent hosts but diagnosis is often delayed. Between December 1975 to October 1988, our two Nephrology Units have encountered five cases of nocardiosis occurring in two post-renal transplant patients, two patients with systemic lupus erythematous (SLE) and one patient with mesangiocapillary glomerulo--nephritis. All were on immunosuppressants at the time. The first three patients presented with predominant pulmonary disease and were cured by combined trimethoprim-sulphamethoxazole (cotrimoxazole) and doxycycline therapy. The patient with limited skin involvement responded to cotrimoxazole alone. However, the last patient with lymphocutaneous disease initially responded to cotrimoxazole (+ chloramphenicol) but developed acute-on-chronic renal failure and relapsed with dose reduction of cotrimoxazole. Alternative treatment with amikacin and doxycycline was instituted with good response. We shall review potential clues that may suggest the diagnosis of nocardiosis and discuss other effective antimicrobial agents.