We identified two types of gamma/delta T-cell clones: (1) BB3+ clones, which express the disulphide-linked form of the gamma/delta heterodimer (type 1 receptor) and carry rearrangements of the C gamma 1 gene; and (2) delta TCS1+ clones, which express the nondisulphide-linked form of the gamma/delta heterodimer (type 2 receptor) and carry rearrangements of the C gamma 2 gene. To determine the joining (J) and variable (V) region usage of the two receptor types, T gamma and T delta gene rearrangements and expression were analyzed in each gamma/delta T-cell clone. The results showed that the J and V regions used by the two receptor types are distinct: clones that express the type 1 receptor carry potentially functional rearrangements in J gamma P-V gamma 9 for gamma and in J delta 1-V delta 2 for delta; and clones that express the type 2 receptor had potentially functional rearrangements in J gamma 2-V gamma 2/V gamma 4 for gamma and in J delta 1-V delta 1 for delta. Therefore, two clearly different gamma/delta receptors (V gamma 9-J gamma P-C gamma 1/V delta 2-J delta 1-C delta and V gamma 2/V gamma 4-J gamma 2-C gamma 2/V delta 1-J delta 1-C delta) predominate in peripheral blood.