We monitored the responses of solid organ transplant recipients (SOTs) to influenza vaccine during consecutive influenza seasons. Standard 1993–1994 trivalent influenza vaccine was given to 68 SOTs and 29 healthy young adults) and hemagglutination-inhibition (HI) antibody titers were determined pre- and post-immunization. Significant rises in geometric mean antibody titers occurred post-immunization for all three antigens in both groups. However) the magnitude of the rise was lower in SOTs (1.5–2.3-fold vs. 8.7–10.4-fold, depending on the antigen) (P < .05), and significantly fewer SOTs had protective HI titers (⩾1:40) for B/Panama/45190 antigens (50% of SOTs vs. 76% of healthy subjects) and for A/Texas/36/91 (H1Nl) antigens (60% vs. 90%). After exclusion of persons with high preimmunization titers, SOTs had significantly reduced frequencies of ⩾4-fold antibody responses compared with those of healthy subjects (23%–38% vs. 86%–100%) (P < .05 for each antigen). When a series of two injections of standard 1994–1995 vaccine was given to 23 SOTs, there was no significant improvement in vaccine response with the second dose. Some SOTs have deficient responses to inactivated influenza vaccines.