A test cross was conducted to analyse some linkage relationships in the chicken. Pea comb (P), naked neck (Na), tardy feathering (t), four erythrocyte alloantigen loci (Ea-C, -D, -I, -P), and the rearrangement break point (RB) of the NM 7092 t(Z;1) chromosome translocation were tested. Significant linkages were found between P and Ea-I (32.9 +/- 4.2), the RB and Ea-D (30.7 +/- 4.3), and t and Ea-D (38 +/- 4.8). The data suggest the linear order of t, Ea-D, and the RB, with t closest to the centromere. Significant linkage was also found between Na and Ea-P (32.4 +/- 4.9), confirming earlier reports.