For a graph G, $$L(G)^2$$
L
(
G
)
2
is the square of the line graph of G – that is, vertices of $$L(G)^2$$
L
(
G
)
2
are edges of G and two edges $$e,f\in E(G)$$
e
,
f
∈
E
(
G
)
are adjacent in $$L(G)^2$$
L
(
G
)
2
if at least one vertex of e is adjacent to a vertex of f and $$e\ne f$$
e
≠
f
. The strong chromatic index of G, denoted by $$s'(G)$$
s
′
(
G
)
, is the chromatic number of $$L(G)^2$$
L
(
G
)
2
. A strong clique in G is a clique in $$L(G)^2$$
L
(
G
)
2
. Finding a bound for the maximum size of a strong clique in a graph with given maximum degree is a problem connected to a famous conjecture of Erdős and Nešetřil concerning strong chromatic index of graphs. In this note we prove that a size of a strong clique in a claw-free graph with maximum degree $$\varDelta $$
Δ
is at most $$\varDelta ^2 + \frac{1}{2}\varDelta $$
Δ
2
+
1
2
Δ
. This result improves the only known result $$1.125\varDelta ^2+\varDelta $$
1.125
Δ
2
+
Δ
, which is a bound for the strong chromatic index of claw-free graphs.